genschema CLI Tool¶

genschema is a command-line utility that generates JSON Schema from one or more JSON documents. It supports multiple input files, stdin input, smart type merging with anyOf/oneOf, pseudo-array detection, and several optional schema refinement comparators.

Features¶

Generate JSON Schema from single or multiple JSON instances
Merge schemas using anyOf or oneOf combinators
Automatic detection of pseudo-arrays (inhomogeneous arrays treated as object-like structures)
Optional comparators: - Format detection (format keyword) - Required properties inference - Empty value handling (null vs absence) - Element deletion in special cases (e.g. pseudo-array markers)
Output to file or stdout
Rich console output with error reporting and timing

Usage¶

genschema [OPTIONS] [INPUTS]...

Arguments¶

INPUTS: Paths to JSON files, or - to read from stdin. Multiple files are allowed. If no inputs are provided, help is shown and program exits.

Options¶

-o, --output OUTPUT: Path to the output JSON Schema file. If omitted, schema is printed to stdout.
--base-of {anyOf,oneOf}: Schema combination strategy when types differ across instances. Default: anyOf
--no-pseudo-array: Disable pseudo-array detection and handling.
--no-format: Disable inference of format keywords (email, date, uri, etc.).
--no-required: Disable automatic population of the required array.
--no-empty: Disable special handling of empty values / missing properties.
--no-delete-element: Disable all DeleteElement comparators (including pseudo-array cleanup).

Examples¶

Read single file and write schema to disk¶

genschema data.json -o schema.json

Multiple files → anyOf combination¶

genschema user1.json user2.json user3.json --base-of anyOf -o schema.json

Read from stdin¶

cat record.json | genschema -

# or with redirection
genschema - < record.json

# piping from another command
curl https://api.example.com/data | genschema -o api-schema.json

Use oneOf instead of anyOf¶

genschema event-log-*.json --base-of oneOf -o events.schema.json

Exit Codes¶

0 — success
1 — invalid JSON, file not found, schema generation error, etc.

Output¶

When writing to stdout, the schema is printed as formatted JSON (indent=2). When writing to file, the same formatted JSON is saved and a success message is shown.

Console also reports:

number of processed JSON instances
elapsed generation time

Implementation Notes¶

The tool is built around a modular Converter class that:

Accepts multiple JSON documents
Applies a chain of comparators/transformers
Supports optional pseudo-array flattening
Uses configurable base combinator (anyOf / oneOf)

Comparators can be selectively disabled via CLI flags.